Influences of Ultrasonic Assistance in High Speed Lapping of Nano ZTA Engineering Ceramic on the Surface Machining Quality

Abstract:

Article Preview

Ultrasonic aided high speed lapping with solid abrasive material was put forward aimed at the
precision finishing of nano ZTA engineering ceramic. Through theoretical analysis and contrast lapping
experiments, the influences of ultrasonic assistance on the surface machining quality were clarified. Research
results show that the maximum undeformed chip thickness in ultrasonic aided lapping is smaller than that in
conventional lapping under the same conditions; ultrasonic assistance is beneficial to enlarging the range of
ductile lapping regime and improving the surface quality of nano ZTA ceramic; with the application of
ultrasonic vibration, smaller surface roughness and more regular surface profile can be obtained.

Abstract: In the present study, zirconia ceramic, crystal and two typical natural granites were ELID ground on a precision grinding machine under the same condition. The surface appearances during the grinding process with different mesh size metal bonded diamond wheels were examined to describe the formation of finely finished granite surfaces. According to the detailed micro-observation of ground surfaces, it can be concluded that the material removal mechanism of the main mineral components for natural granites are really similar to other brittle materials during ELID grinding process. However, the differences of material performances cause the granite materials to be larger critical grain depth of cut and more ductile during finely grinding.

Abstract: On the basis of analyzing the brittleness, ductileity, and the removal mechanisms of the^nano-ZrO2 Ceramics, the critical ductile grinding depth formula of the nano-ceramics was established. Due to superductileity of the nano-ZrO2 ceramics, it couldn’t apply the formula of the common engineering ceramic material according to experimental results. The value of material coefficient ζ has relations with not only the material characteristics but also the processing methods and the processing parameters. It was proved that ζ has great effects on the accuracy of theoretical
calculation. Experimental results showed that the critical ductility grinding depth of the nano-ZrO2 ceramics is up to 12 µm in common grinding methods, while in ultrasonic grinding is up to 20µm. The grinding chips with and without ultrasonic vibration assistance were discussed.

Abstract: Based on impulse theories and indentation fracture mechanics, the motion model of the contact between abrasive particle and workpiece in workpiece two-dimension ultrasonic vibration grinding (WTDUVG) was analyzed, and the critical condition of ultrasonic vibration grinding brittle-ductile transition was analyzed theoretically, furthermore the critical cutting depths of a grain under different grinding conditions were obtained by Matlab programs. In this work, the ultrasonic vibration and conventional diamond grinding of Al2O3/ZrO2 nanoceramics were performed in order to investigate the effect of workpiece ultrasonic vibration on the brittle-ductile transition mechanism, the effect of grit size, worktable speed and grinding depth on the critical depth of cut were studied by grinding experiments. the micro-topography of the grinding surface was observed by AFM and SEM. Experiment indicated that only when the grinding depth less than critical grinding depth, ductile regime grinding of ceramics can be realized, the appropriate grinding parameter on surface finish are suggested.

Abstract: Hard and brittle materials such as silicon and ceramic materials are difficult to machining due to their brittle properties. By the ductile-mode machining, delicate features with high accuracy can be created on these materials by mechanical micro/nano machining. This paper introduced the experimental study on the ductile-mode milling of ceramics. First, the experimental background and plans have been introduced. Then, on the sub-micron milling center, experimental results show that ductile-mode machining can be achieved. Both machining parameters and machining conditions are very important in order to realize the ductile-mode machining